I was thinking of the largest problem blizzard always gives us when trying to balance arena. The old "that would break pve" argument has prevented pvp in wow from really being all it has the potential to be.

After looking at different solutions to this problem i came up with the idea of something i call "Class Buffs." Each class would have a passive "buff" assigned to their character that would correspond with the class they are playing. Warriors would have warrior buff, priests would have priest buff, and so on... These buffs would only be active in Arena and RBGs. The buffs would be active upon entering a match.

Each buff would include flat percentages that impact that classes effectiveness in pvp. Things such as:
-Damage done
-Damage taken
-Healing done
-Healing Recieved

All that would have to be done to balance classes would then be to tweak percentages based on the performance of each class. If it is obvious that warriors are way overpowered because they do to much damage then the damage done percentage would be toned down.

Two examples could be:
-Warrior
Warriors deal 85% damage to other players
The rest would be 100%

-Priest
Priests heal players for 125%
Priests take 15% less damage in pvp

This system would solve any issue that comes with changing the damage/healing of abilities and thus breaking the cycle of pve. Any aspect of any class could be tweaked to make them more evenly matched in pvp. We all know rogues get killed way to easily so,

Rogue: Rogues take 20% less damage from players.

The possibilities are endless, using statistics and mathematical analysis im sure blizzard could potentially create an environment where each class is almost exactly in tune with each other.

Obviously blizzard could coordinate this with the nerfing of broken mechanics such as warrior avatar immunity to create even more efficient balancing, but as a whole this would be the way in which balancing takes place.

If you haven't noticed yet, Blizzard is not tweaking numbers based on PvP anymore at all, because PvE is almost perfectly balanced.currently. They are tweaking mechanics that revolve around most common things used in PvP.
Like Chaosbolt nerf, they reduced the damage on initial hit, but gave it a dot. Now it wont global a player and still doing almost exact dps in PvE.
Same thing with Frostbomb, in PvE nobody uses Fireblast glyph, so smart thing to adjust is the glyph everyone uses. Now the 4sec trigger and -20% baseline damagereduction on players makes it "balanced" spell in PvP and keeps frostspec the same on PvE.

What you suggest wouldn't work, because you can't just give percentage to buff or nerf one class's all spells and abilities, when there are things that hit really hard or close to nothing at all. Same with healing.

Best way to balance would be to give every ability ingame a percentage it does in PvP combat, but for some odd reason Blizzard doesn't want to do it. Maybe because it's many times more work to make patches and hotfixes if you have to calculate every spell to do different damage/healing in Pve and PvP.

I think this is a good idea but I still don't like it, I want the game abilities to be exactly the same everywhere and I think arena is pretty much a lost cause anyway, sometimes it will be good and sometimes it will be shit and even when it's decent or good people are going to cry.